Diazepam IM Dosing Equivalent for Catatonia
Give 10 mg of diazepam intramuscularly as the equivalent dose to 2 mg oral lorazepam for catatonia treatment. 1, 2
Dosing Rationale
The conversion is based on established benzodiazepine equivalency and specific catatonia treatment evidence:
- Diazepam 10 mg is equivalent to lorazepam 2-2.5 mg as a sedative, making 10 mg diazepam the appropriate substitute for your intended 2 mg lorazepam dose 1
- In catatonia treatment protocols, when 2 mg lorazepam IM fails, 10 mg diazepam IV is the standard next step, demonstrating these doses are considered therapeutically equivalent in this specific clinical context 2
- The study examining catatonia in mood disorders used exactly this dosing strategy: 2 mg lorazepam IM initially, followed by 10 mg diazepam if needed, with 100% response rate within 24 hours 2
Administration Considerations
Route differences matter less than you might expect:
- Lorazepam absorption is excellent via IM route, reaching peak levels at approximately 1.15 hours with 95.9% bioavailability 3
- Diazepam IM absorption is actually less reliable than lorazepam IM - diazepam is better absorbed orally than intramuscularly, while lorazepam maintains consistent absorption regardless of route 1
- Despite this pharmacokinetic limitation, diazepam IM remains clinically effective for catatonia when lorazepam is unavailable 2
Monitoring Requirements
Prepare for respiratory depression:
- Monitor oxygen saturation continuously, as benzodiazepines carry increased risk of apnea 4, 5
- Have respiratory support immediately available 6
- Watch for hypotension, particularly in elderly or frail patients 4
- Consider dose reduction if patient has underlying respiratory disease, hepatic impairment, or is elderly 4, 5
Expected Response Timeline
Catatonia should improve rapidly:
- In the catatonia treatment study, 83.3% of patients responded to lorazepam IM within hours, and all patients achieved full remission within 24 hours using the lorazepam-diazepam strategy 2
- If no improvement occurs within 2 hours, consider repeating the dose (another 10 mg diazepam IM) 2
- If catatonia persists after benzodiazepine trial, electroconvulsive therapy may be necessary - 9 of 18 patients in one study required ECT for complete resolution 7
Critical Pitfall to Avoid
Do not underdose - using less than 10 mg diazepam IM would provide subtherapeutic benzodiazepine effect compared to the intended 2 mg lorazepam dose, potentially delaying catatonia resolution and increasing morbidity risk 1, 2